CN112340700A - System and method for recycling chlorine from waste mother liquor of bleaching powder - Google Patents
System and method for recycling chlorine from waste mother liquor of bleaching powder Download PDFInfo
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- CN112340700A CN112340700A CN202011392820.1A CN202011392820A CN112340700A CN 112340700 A CN112340700 A CN 112340700A CN 202011392820 A CN202011392820 A CN 202011392820A CN 112340700 A CN112340700 A CN 112340700A
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- chlorine
- drying tower
- pipe
- mother liquor
- sulfuric acid
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- 239000000460 chlorine Substances 0.000 title claims abstract description 104
- 229910052801 chlorine Inorganic materials 0.000 title claims abstract description 101
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 title claims abstract description 97
- ZKQDCIXGCQPQNV-UHFFFAOYSA-N Calcium hypochlorite Chemical compound [Ca+2].Cl[O-].Cl[O-] ZKQDCIXGCQPQNV-UHFFFAOYSA-N 0.000 title claims abstract description 61
- 239000012452 mother liquor Substances 0.000 title claims abstract description 59
- 239000002699 waste material Substances 0.000 title claims abstract description 56
- 239000007844 bleaching agent Substances 0.000 title claims abstract description 55
- 238000000034 method Methods 0.000 title claims abstract description 34
- 238000004064 recycling Methods 0.000 title description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 167
- 238000001035 drying Methods 0.000 claims abstract description 131
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 106
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 82
- 238000000746 purification Methods 0.000 claims abstract description 49
- 239000007789 gas Substances 0.000 claims abstract description 47
- 239000012071 phase Substances 0.000 claims abstract description 41
- 239000007792 gaseous phase Substances 0.000 claims abstract description 8
- 239000001117 sulphuric acid Substances 0.000 claims abstract description 8
- 235000011149 sulphuric acid Nutrition 0.000 claims abstract description 8
- OSVXSBDYLRYLIG-UHFFFAOYSA-N dioxidochlorine(.) Chemical compound O=Cl=O OSVXSBDYLRYLIG-UHFFFAOYSA-N 0.000 claims description 36
- 239000007788 liquid Substances 0.000 claims description 21
- 239000007791 liquid phase Substances 0.000 claims description 21
- 239000004155 Chlorine dioxide Substances 0.000 claims description 15
- 235000019398 chlorine dioxide Nutrition 0.000 claims description 15
- 238000007599 discharging Methods 0.000 claims description 3
- 239000000945 filler Substances 0.000 claims description 2
- 230000005611 electricity Effects 0.000 claims 1
- 238000002360 preparation method Methods 0.000 abstract description 4
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 43
- 239000011575 calcium Substances 0.000 description 22
- 239000012535 impurity Substances 0.000 description 16
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 14
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 229910052791 calcium Inorganic materials 0.000 description 12
- 239000000243 solution Substances 0.000 description 12
- 239000001110 calcium chloride Substances 0.000 description 10
- 229910001628 calcium chloride Inorganic materials 0.000 description 10
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 8
- 239000006227 byproduct Substances 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 7
- 239000000047 product Substances 0.000 description 7
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 6
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 6
- 239000002253 acid Substances 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- 239000011734 sodium Substances 0.000 description 6
- 229910052708 sodium Inorganic materials 0.000 description 6
- YALMXYPQBUJUME-UHFFFAOYSA-L calcium chlorate Chemical compound [Ca+2].[O-]Cl(=O)=O.[O-]Cl(=O)=O YALMXYPQBUJUME-UHFFFAOYSA-L 0.000 description 5
- 238000005660 chlorination reaction Methods 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- 239000003513 alkali Substances 0.000 description 4
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 4
- 235000011121 sodium hydroxide Nutrition 0.000 description 4
- 238000012423 maintenance Methods 0.000 description 3
- 230000001105 regulatory effect Effects 0.000 description 3
- 239000011780 sodium chloride Substances 0.000 description 3
- 239000002351 wastewater Substances 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000004061 bleaching Methods 0.000 description 2
- 239000012267 brine Substances 0.000 description 2
- TVWHTOUAJSGEKT-UHFFFAOYSA-N chlorine trioxide Chemical compound [O]Cl(=O)=O TVWHTOUAJSGEKT-UHFFFAOYSA-N 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 208000021302 gastroesophageal reflux disease Diseases 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 2
- 239000005708 Sodium hypochlorite Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- QBWCMBCROVPCKQ-UHFFFAOYSA-N chlorous acid Chemical compound OCl=O QBWCMBCROVPCKQ-UHFFFAOYSA-N 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 239000000645 desinfectant Substances 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B7/00—Halogens; Halogen acids
- C01B7/01—Chlorine; Hydrogen chloride
- C01B7/07—Purification ; Separation
- C01B7/0743—Purification ; Separation of gaseous or dissolved chlorine
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Treating Waste Gases (AREA)
Abstract
The invention belongs to the technical field of bleaching powder preparation, and particularly relates to a system and a method for recovering chlorine from a waste mother liquor of bleaching powder. The utility model provides a system for retrieve chlorine from useless mother liquor of bleaching powder, includes the acidolysis cauldron, is connected with hydrochloric acid pipe and useless mother liquor pipe on the acidolysis cauldron, and the gaseous phase export of acidolysis cauldron has the purifying column through the pipe connection, is connected with the circulation cold water pipe on the purifying column, and the gaseous phase export of purifying column has first drying tower through the pipe connection, is connected with the dilute sulphuric acid pipe of circulation on the first drying tower, and the pipe connection that passes through of first drying tower has the second drying tower, is connected with concentrated sulphuric acid pipe on the second drying tower. A method for recovering chlorine from waste mother liquor of bleaching powder comprises the following steps: s1: continuously adding hydrochloric acid and waste mother liquor into an acidolysis kettle; s2: sending acidolysis gas into a purification tower; s3: and then the gas phase passes through a first drying tower and a second drying tower for drying. The invention provides a system and a method for performing harmless treatment on a bleaching powder waste mother liquor and obtaining high-quality chlorine.
Description
Technical Field
The invention belongs to the technical field of bleaching powder preparation, and particularly relates to a system and a method for recovering chlorine from a waste mother liquor of bleaching powder.
Background
The bleaching powder essence is a high-effective inorganic bleaching disinfectant, its main component is Ca (ClO)2The main two technological routes for producing the bleaching powder are calcium process and sodium process. The calcium bleaching powder contains 3Ca (ClO) as effective component2·2Ca(OH)2·2H2O, by Ca (OH)2And Cl2The preparation method comprises the following steps of. The main component of the sodium bleaching powder is Ca (ClO)2·2H2O, by NaOH, Ca (OH)2And Cl2The preparation method comprises the following steps of.
The calcium bleaching powder produces about 6 to 8 tons of waste mother liquor per ton of product, and the waste mother liquor contains about 10 percent of Ca (ClO)2、20％CaCl2And about 1% Ca (ClO)3)2(ii) a The byproduct of sodium bleaching powder is about 5 tons of waste mother liquor per ton of product, and the waste mother liquor contains 3 percent of Ca (ClO)2And 20% NaCl and about 1% Ca (ClO)3)2. Because the waste mother liquor contains Ca (ClO)2Direct discharge of ClO pollutes water and environment-The root has strong oxidizing property and is related to severe corrosion of a wastewater treatment deviceTherefore, the equipment needs to carry out innocent treatment on the byproduct mother liquor of the bleaching powder.
In the fine apparatus for producing of traditional bleaching powder, the processing of waste mother liquor usually comprises two units of batch acidolysis, alkali liquor absorption waste chlorine, and whole process is batch operation, and its process flow is:
firstly, acidolysis of waste mother liquor: adding hydrochloric acid, hydrochloric acid and Ca (ClO)2Reaction to form CaCl2And Cl2When the pH value of the mother liquor is<3, when the reaction reaches the end point, stopping adding the acid; the liquid phase after acidolysis by the calcium method is CaCl2The solution is generally sent to evaporation and drying procedures to produce solid calcium chloride; the liquid phase after the acidolysis by the sodium method is NaCl solution (containing a small amount of CaCl)2) Typically sent to a brine process or returned to a brine well.
Secondly, absorbing waste chlorine gas by alkali liquor: since the waste mother liquor contains Ca (ClO)3)2，Ca(ClO3)2Reaction with hydrochloric acid will produce ClO2，ClO2The chlorine gas is a gas with explosion danger, is sensitive to light, heat, vibration, impact, friction and the like, and chlorine dioxide contained in the chlorine gas can be unfavorable for chlorination reaction; the acidolysis is a batch reaction, and air cannot be mixed in the process of system emptying and charging; the chlorine gas contains air and ClO due to the above two factors2And a large amount of water vapor, the impurity content is high, and qualified bleaching powder cannot be produced after the bleaching powder is recycled. So the waste chlorine is generally sent to an alkaline washing tower, and the waste chlorine is absorbed by dilute sodium hydroxide solution and acidolyzed, and sodium hypochlorite solution is by-produced.
Although the traditional bleaching powder waste mother liquor treatment process solves the problem of waste mother liquor discharge, the process has the following limitations:
1. batch operation, high labor intensity and difficulty in realizing full automation
2. Large consumption of acid and alkali: the traditional process consumes about 0.4 ton of 31 percent hydrochloric acid and 0.24 ton of 50 percent liquid caustic soda per ton of calcium method waste mother liquor, and about 0.12 ton of 31 percent hydrochloric acid and 0.08 ton of 50 percent liquid caustic soda per ton of sodium method waste mother liquor, and the extra cost brought by waste liquor treatment causes the production cost of the bleaching powder essence to be high.
3. The chlorine can not be recycled to the bleaching powder device: chlorine is the main raw material for producing the bleaching powder, and is recycled to the bleaching powder device to be the most ideal place for removing the chlorine by acidolysis, so that the chlorine consumption quota can be reduced, and the alkali consumption required by absorption of waste chlorine can be reduced. But the waste mother liquor acidolysis byproduct chlorine has high impurity content, and qualified bleaching powder cannot be produced after recycling.
Disclosure of Invention
In order to solve the above problems in the prior art, the present invention aims to provide a system and a method for performing a harmless treatment on a bleaching powder waste mother liquor to obtain high-quality chlorine gas.
The technical scheme adopted by the invention is as follows:
the utility model provides a system for retrieve chlorine from useless mother liquor of bleaching powder essence, including the acidolysis cauldron, be connected with the useless mother liquor pipe that is used for adding hydrochloric acid in succession and adds useless mother liquor in succession on the acidolysis cauldron, the gaseous phase export of acidolysis cauldron has the purifying column through the pipe connection, be connected with the circulation cold water pipe that is used for the circulation to add the refrigerated water on the purifying column, the gaseous phase export of purifying column has first drying tower through the pipe connection, be connected with the circulation dilute sulphuric acid pipe that is used for the circulation to add dilute sulphuric acid on the first drying tower, the gaseous phase export of first drying tower has the second drying tower through the pipe connection, be connected with the concentrated sulphuric acid pipe that is used for adding concentrated sulphuric acid on the second drying tower.
Hydrochloric acid is continuously added from the hydrochloric acid pipe, and waste mother liquor is continuously added from the waste mother liquor pipe, so that the waste mother liquor and the hydrochloric acid are fully reacted. After acidolysis, the liquid phase is calcium chloride solution, and is sent out of the battery compartment for evaporation and drying, and a solid calcium chloride product is obtained as a byproduct. The acidolysis gas phase mainly contains chlorine, water vapor and a small amount of chlorine dioxide, and is sent to a purification and drying unit for removing impurities. When the hydrochloric acid and the waste mother liquor are continuously added, the problem that air is mixed in a gas phase is avoided, the workload of operation and maintenance is reduced, correspondingly, the content of impurities in the chlorine is less, and the chlorine is convenient to carry out subsequent treatment and reuse.
The cold water and the acidolysis gas are in full countercurrent contact in the purification tower; in this process, about 90% of the moisture in the chlorine gas is condensed off, simultaneously because of the ClO2Has high solubility in cold water, and most of gas phaseOf ClO (ClO)2Is absorbed by the circulating cold water. After the gas phase passes through the scrubber, most of the ClO2Is removed, and 90 to 95 percent of water is condensed.
The purified gas phase also contains about 5 percent of water, and the water content is reduced to 100ppm after the gas phase is dried by a sulfuric acid drying tower with two stages of filling materials and bubble caps connected in series. Most of the impurities in the chlorine gas are removed, the quality meets the production requirement of the bleaching powder, and the chlorine gas is pressurized by a chlorine press and then sent back to the bleaching powder device.
As a preferable scheme of the invention, a liquid phase outlet of the acidolysis kettle is connected with a liquid phase pipe, a pH monitor is arranged on the liquid phase pipe, a hydrochloric acid electromagnetic valve is arranged on the hydrochloric acid pipe, and the pH monitor is electrically connected with the hydrochloric acid electromagnetic valve. The pH monitor can monitor the pH value of the liquid phase of the acidolysis kettle in real time, and then the pH value is controlled within the range of 2-3, so that the calcium hypochlorite and the calcium chlorate in the solution can be ensured to be completely reacted. The hydrochloric acid electromagnetic valve adjusts the adding speed of the hydrochloric acid according to the numerical value of the pH monitor.
In a preferred embodiment of the present invention, the gas phase outlet of the acidolysis reactor is connected to the lower section of the purification column via a pipeline, and the outlet end of the circulating cold water pipe is connected to the upper section of the purification column. The wet chlorine gas in acidolysis gas phase (50-60 deg.c) is fed into the bottom of purification tower, the circulating cold water is cooled by using chilled water (5-10 deg.c) in purification tower cooler and fed into the top of purification tower, and directly contacted with acidolysis gas phase in counter-current mode, and the circulating cold water can absorb most of chlorine dioxide in acidolysis gas phase, and can cool the chlorine gas to 15-20 deg.c, and the water content in the chlorine gas is about 90-95% and is condensed.
As a preferred scheme of the invention, the inlet end of the circulating cold water pipe is connected with the lower end of the purification tower, and a purification tower circulating pump and a purification tower cooler are arranged on the circulating cold water pipe; the circulating cold water pipe is also connected with a chlorine water pipe for discharging chlorine water containing chlorine dioxide, the purification tower is provided with a chlorine water level monitor, the chlorine water pipe is provided with a chlorine water electromagnetic valve, and the chlorine water level monitor is electrically connected with the chlorine water electromagnetic valve. The circulating pump of the purification tower recycles the cold water, and the cooler of the purification tower cools the water. The chlorine water liquid level monitor monitors the liquid level, and when the liquid level exceeds a set value, the chlorine water electromagnetic valve is triggered to be opened, and then the cold water containing chlorine dioxide is discharged.
As a preferable scheme of the invention, the outlet end of the circulating dilute sulphuric acid pipe is connected to the upper section of the first drying tower, and the gas phase outlet of the purifying tower is connected to the lower section of the first drying tower through a pipeline; the inlet end of the circulating dilute sulfuric acid pipe is connected to the lower end of the first drying tower, and a circulating pump of the first drying tower and a cooler of the first drying tower are mounted on the circulating dilute sulfuric acid pipe; and a dilute sulfuric acid discharge pipe is connected to the circulating dilute sulfuric acid pipe, a dilute sulfuric acid electromagnetic valve is mounted on the dilute sulfuric acid discharge pipe, a dilute sulfuric acid liquid level monitor is mounted on the second drying tower, and the dilute sulfuric acid liquid level monitor is electrically connected with the dilute sulfuric acid electromagnetic valve. The first drying tower is a bulk packed tower, chlorine gas after impurity removal of the purifying tower enters the lower section of the drying tower of the first drying tower, circulating dilute sulfuric acid (with the sulfuric acid concentration of 75-80%) is sent out by a circulating pump of the first drying tower, and is cooled to 12-15 ℃ by using chilled water through a cooler of the first drying tower, and then enters the upper section of the first drying tower to be in countercurrent contact with the chlorine gas to remove water in the chlorine. The concentration of the acid discharged from the bottom of the first drying tower is controlled to be 75-80%. The water in the chlorine is absorbed by the sulfuric acid to release heat, and the heat is mostly carried away by the first drying tower cooler.
In a preferred embodiment of the present invention, a sulfuric acid reflux pipe is further connected between the lower section of the second drying tower and the lower section of the first drying tower. The second drying tower is a bubble cap tower, chlorine at the outlet of the first drying tower enters the lower section of the second drying tower and contacts with 98% concentrated sulfuric acid through a bubble cap, and after the concentrated sulfuric acid absorbs moisture in the chlorine, the concentration is reduced to 90% -95%, and then the chlorine flows into the first drying tower through a sulfuric acid return pipe. The concentration of the sulfuric acid in the first drying tower is reduced to 75-80% after the sulfuric acid absorbs water. The dilute sulfuric acid is delivered out of the battery limit zone by a first tower circulating pump under the control of a liquid level regulating system.
As a preferable scheme of the invention, the gas-phase outlet of the second drying tower is connected with a chlorine compressor through a pipeline, and the outlet of the chlorine compressor is connected with a bleaching powder device through a pipeline. The water content of the chlorine gas is reduced to be less than 100ppm after the drying of the secondary sulfuric acid, so that the quality of the purified and dried chlorine gas meets the requirement of the production of the bleaching powder, and the chlorine gas is compressed by a chlorine compressor and then sent back to the chlorination process of the bleaching powder device.
A method for recovering chlorine from waste mother liquor of bleaching powder comprises the following steps:
s1: continuously adding hydrochloric acid and waste mother liquor into an acidolysis kettle; controlling the addition amount of hydrochloric acid according to the pH value of the solution at the outlet of the acidolysis kettle, wherein the pH value is set to be 2-3, so as to ensure that calcium hypochlorite and calcium chlorate in the solution are completely reacted; the liquid phase after acidolysis by the calcium method is a calcium chloride solution, and the calcium chloride solution is sent out of the battery compartment to be evaporated and dried, and a solid calcium chloride product is produced as a byproduct; the acidolysis gas phase mainly contains chlorine, water vapor and a small amount of chlorine dioxide and is sent to a purification and drying unit for removing impurities;
s2: sending acidolysis gas into a purification tower to be fully contacted with circulating cold water; the condensed cold water dissolved with chlorine dioxide and chlorine is sent out of the battery limit by a circulating pump of the purification tower under the automatic control of a liquid level adjusting system of the purification tower;
s3: and then the gas phase is dried by a first drying tower and a second drying tower which are connected in series. The first drying tower is a bulk packed tower, chlorine gas after impurity removal of the purifying tower enters the lower section of the drying tower of the first drying tower, circulating dilute sulfuric acid (the concentration of the sulfuric acid is 75-80%) is sent out by a circulating pump of the first drying tower, and is cooled to 12-15 ℃ by a first drying tower cooler through chilled water, and then enters the upper section of the first drying tower to be in countercurrent contact with the chlorine gas to remove water in the chlorine. The concentration of the acid discharged from the tower bottom is controlled to be 75-80%. The water in the chlorine is absorbed by the sulfuric acid to release heat, and the heat is mostly carried away by the first drying tower cooler. The second drying tower is a bubble cap tower, chlorine at the outlet of the first drying tower enters the bottom of the second drying tower and contacts with 98% concentrated sulfuric acid through a bubble cap, and after the concentrated sulfuric acid absorbs moisture in the chlorine, the concentration is reduced to 90% -95%, and then the chlorine automatically flows into the first drying tower. After absorbing water, the concentration of the sulfuric acid in the first drying tower is reduced to 75-80%, and the dilute sulfuric acid is conveyed out of the battery compartment by the first tower circulating pump under the control of the liquid level adjusting system. The water content of the chlorine gas is reduced to be less than 100ppm after the drying of the secondary sulfuric acid, so that the quality of the purified and dried chlorine gas meets the requirement of the production of the bleaching powder, and the chlorine gas is compressed by a chlorine compressor and then sent back to the chlorination process of the bleaching powder device.
The invention has the beneficial effects that:
1. the invention avoids the problem of air mixing in the gas phase by continuously adding the hydrochloric acid and the waste mother liquor, reduces the workload of operation and maintenance, correspondingly, has less impurity content in the chlorine gas, and is convenient for subsequent treatment and recycling of the chlorine gas.
2. The addition amount of hydrochloric acid is controlled according to the pH value of the liquid phase at the outlet of the acidolysis kettle, the pH value is controlled within the range of 2-3, and the complete reaction of calcium hypochlorite and calcium chlorate in the bleaching solution is ensured.
3. The impurities in the acidolysis gas phase are removed by adopting a purification tower, and circulating cold water is in countercurrent contact with the acidolysis gas phase in the purification tower, so that the chlorine dioxide in the gas phase is absorbed while the water in the gas phase is condensed. And (3) carrying out sulfuric acid drying on the chlorine by adopting a two-stage series drying tower with a filler and a bubble cap to ensure that the water content of the chlorine is less than 100ppmwt, thus obtaining the high-quality chlorine for producing the bleaching powder.
Drawings
Fig. 1 is a schematic structural view of the present invention.
In the figure, 1-acidolysis kettle; 2-a purification tower; 3-circulating cold water pipe; 4-a first drying tower; 5-circulating dilute sulfuric acid pipe; 6-a second drying tower; 7-a liquid phase tube; 8-chlorine water pipe; 9-chlorine press; 11-hydrochloric acid tube; 12-spent mother liquor pipe; 21-chlorine water level monitor; 31-a purification tower circulation pump; 32-a purification tower cooler; 51-first drying tower circulation pump; 52-first drying tower cooler; 53-dilute sulfuric acid discharge pipe; 61-concentrated sulfuric acid tube; 62-dilute sulfuric acid level monitor; 63-sulfuric acid reflux pipe; 71-a PH monitor; 81-chlorine water electromagnetic valve; 111-hydrochloric acid solenoid valve; 531-dilute sulfuric acid solenoid valve.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
Example 1:
as shown in fig. 1, the system for recovering chlorine from waste mother liquor of bleaching powder according to the embodiment includes an acidolysis kettle 1, a hydrochloric acid pipe 11 for continuously adding hydrochloric acid and a waste mother liquor pipe 12 for continuously adding waste mother liquor are connected to the acidolysis kettle 1, a gas phase outlet of the acidolysis kettle 1 is connected to a purification tower 2 through a pipeline, a circulating cold water pipe 3 for circularly adding chilled water is connected to the purification tower 2, a first drying tower 4 is connected to the gas phase outlet of the purification tower 2 through a pipeline, a circulating dilute sulfuric acid pipe 5 for circularly adding dilute sulfuric acid is connected to the first drying tower 4, a second drying tower 6 is connected to the gas phase outlet of the first drying tower 4 through a pipeline, and a concentrated sulfuric acid pipe 61 for adding concentrated sulfuric acid is connected to the second drying tower 6.
Hydrochloric acid is continuously added from the hydrochloric acid pipe 11, and waste mother liquor is continuously added from the waste mother liquor pipe 12, so that the waste mother liquor and the hydrochloric acid are fully reacted. The main reactions taking place in the acidolysis vessel 1 are as follows:
Ca(ClO)2+4HCl＝CaCl2+2Cl2↑+2H2O；
Ca(ClO3)2+4HCl→2ClO2↑+Cl2↑+CaCl2+2H2O。
the liquid phase after acidolysis by the calcium method is a calcium chloride solution, and the calcium chloride solution is sent out of the battery compartment to be evaporated and dried, and a solid calcium chloride product is produced as a byproduct. The liquid phase after the sodium acidolysis is NaCl solution (containing a small amount of CaCl)2) And returning the treated waste water to a well or sending the treated waste water to a waste water plant. The acidolysis gas phase mainly contains chlorine, water vapor and a small amount of chlorine dioxide, and is sent to a purification and drying unit for removing impurities.
When the hydrochloric acid and the waste mother liquor are continuously added, the problem that air is mixed in a gas phase is avoided, the workload of operation and maintenance is reduced, correspondingly, the content of impurities in the chlorine is less, and the chlorine is convenient to carry out subsequent treatment and reuse. The liquid phase outlet of the acidolysis kettle 1 is connected with a liquid phase pipe 7, a pH monitor 71 is arranged on the liquid phase pipe 7, a hydrochloric acid electromagnetic valve 111 is arranged on the hydrochloric acid pipe 11, and the pH monitor 71 is electrically connected with the hydrochloric acid electromagnetic valve 111. The pH monitor 71 can monitor the pH value of the liquid phase of the acidolysis kettle 1 in real time, and then control the pH value within the range of 2-3, so that the calcium hypochlorite and the calcium chlorate in the solution can be ensured to be completely reacted. The hydrochloric acid solenoid valve 111 adjusts the hydrochloric acid addition rate according to the value of the pH monitor 71.
The cold water and the acidolysis gas are fully carried out in the purification tower 2Countercurrent contact; in this process, about 90% of the moisture in the chlorine gas is condensed off, simultaneously because of the ClO2High solubility in cold water, most of the ClO in the gas phase2Is absorbed by the circulating cold water. After the gas phase passes through the scrubber, most of the ClO2Is removed, and 90 to 95 percent of water is condensed.
The purified gas phase also contains about 5 percent of water, and the water content is reduced to 100ppm after the gas phase is dried by a sulfuric acid drying tower with two stages of filling materials and bubble caps connected in series. Most of the impurities in the chlorine gas are removed, the quality meets the production requirement of the bleaching powder, and the chlorine gas is pressurized by a chlorine compressor 9 and then sent back to the bleaching powder device.
Furthermore, the gas phase outlet of the acidolysis kettle 1 is connected to the lower section of the purification tower 2 through a pipeline, and the outlet end of the circulating cold water pipe 3 is connected to the upper section of the purification tower 2. The acidolysis gas-phase wet chlorine (with the temperature of 50-60 ℃) enters the bottom of the purification tower 2, the circulating cold water is cooled by chilled water (with the temperature of 5-10 ℃) through a purification tower cooler 32 and then enters the top of the purification tower 2 to be in direct countercurrent contact with the acidolysis gas phase, the circulating cold water absorbs most of the chlorine dioxide in the acidolysis gas phase, the chlorine is cooled to 15-20 ℃, and about 90-95% of water in the chlorine is condensed.
Furthermore, the inlet end of the circulating cold water pipe 3 is connected to the lower end of the purification tower 2, and a purification tower circulating pump 31 and a purification tower cooler 32 are installed on the circulating cold water pipe 3; the circulating cold water pipe 3 is also connected with a chlorine water pipe 8 for discharging chlorine water containing chlorine dioxide, the purification tower 2 is provided with a chlorine water level monitor 21, the chlorine water pipe 8 is provided with a chlorine water electromagnetic valve 81, and the chlorine water level monitor 21 is electrically connected with the chlorine water electromagnetic valve 81. The purification tower circulation pump 31 circulates the cold water, and the purification tower cooler 32 cools the water. The chlorine level monitor 21 monitors the liquid level and triggers the chlorine solenoid valve 81 to open when the liquid level exceeds a set value, and then the cold water containing chlorine dioxide is discharged.
In order to ensure that the gas phase is fully contacted with the dilute sulfuric acid in the first drying tower 4, the outlet end of the circulating dilute sulfuric acid pipe 5 is connected to the upper section of the first drying tower 4, and the gas phase outlet of the purifying tower 2 is connected to the lower section of the first drying tower 4 through a pipeline; the inlet end of the circulating dilute sulfuric acid pipe 5 is connected to the lower end of the first drying tower 4, and a first drying tower circulating pump 51 and a first drying tower cooler 52 are installed on the circulating dilute sulfuric acid pipe 5; the circulating dilute sulfuric acid pipe 5 is connected with a dilute sulfuric acid discharge pipe 53, a dilute sulfuric acid electromagnetic valve 531 is installed on the dilute sulfuric acid discharge pipe 53, a dilute sulfuric acid liquid level monitor 62 is installed on the second drying tower 6, and the dilute sulfuric acid liquid level monitor 62 is electrically connected with the dilute sulfuric acid electromagnetic valve 531. The first drying tower 4 is a bulk packed tower, the chlorine gas after impurity removal in the purifying tower 2 enters the lower section of the drying tower of the first drying tower 4, the circulating dilute sulfuric acid (with the sulfuric acid concentration of 75-80%) is sent out by a circulating pump 51 of the first drying tower, and is cooled to 12-15 ℃ by chilled water through a cooler 52 of the first drying tower, and then enters the upper section of the first drying tower 4 to be in countercurrent contact with the chlorine gas to remove the water in the chlorine gas. The concentration of the acid discharged from the bottom of the first drying tower 4 is controlled to be 75-80%. The water in the chlorine gas is absorbed by the sulfuric acid and gives up heat, which is largely removed by the first drying tower cooler 52.
In order to make the sulfuric acid fully utilized, a sulfuric acid return pipe 63 is connected between the lower section of the second drying tower 6 and the lower section of the first drying tower 4. The second drying tower 6 is a bubble cap tower, the chlorine gas at the outlet of the first drying tower 4 enters the lower section of the second drying tower 6 and contacts with 98% concentrated sulfuric acid through a bubble cap, and after the concentrated sulfuric acid absorbs moisture in the chlorine gas, the concentration is reduced to 90% -95%, and then the chlorine gas flows into the first drying tower 4 through a sulfuric acid return pipe 63. The concentration of the sulfuric acid in the first drying tower 4 is reduced to 75-80% after absorbing water. The dilute sulfuric acid is delivered out of the battery limit zone by a first tower circulating pump under the control of a liquid level regulating system.
Further, the gas phase outlet of the second drying tower 6 is connected with a chlorine compressor 9 through a pipeline, and the outlet of the chlorine compressor 9 is connected with a bleaching powder device through a pipeline. The water content of the chlorine gas is reduced to be less than 100ppm after the drying of the secondary sulfuric acid, so that the quality of the purified and dried chlorine gas meets the requirement of the production of the bleaching powder, and the chlorine gas is compressed by a chlorine compressor 9 and then sent back to the chlorination process of the bleaching powder device.
Example 2:
as shown in FIG. 1, the method for recovering chlorine from waste mother liquor of bleaching powder of this embodiment comprises the following steps:
s1: continuously adding hydrochloric acid and waste mother liquor into an acidolysis kettle 1; controlling the addition amount of hydrochloric acid according to the pH value of the solution at the outlet of the acidolysis kettle 1, wherein the pH value is set to be 2-3, so as to ensure that calcium hypochlorite and calcium chlorate in the solution are completely reacted; the liquid phase after acidolysis by the calcium method is a calcium chloride solution, and the calcium chloride solution is sent out of the battery compartment to be evaporated and dried, and a solid calcium chloride product is produced as a byproduct; the acidolysis gas phase mainly contains chlorine, water vapor and a small amount of chlorine dioxide and is sent to a purification and drying unit for removing impurities;
s2: sending acidolysis gas into a purification tower 2, and fully contacting with circulating cold water; the condensed cold water dissolved with chlorine dioxide and chlorine is sent out of the battery limits by a circulating pump 31 of the purification tower under the automatic control of a liquid level regulating system of the purification tower 2;
s3: the gas phase is dried by passing through a first drying tower 4 and a second drying tower 6 connected in series. The first drying tower 4 is a bulk packed tower, the chlorine gas after impurity removal of the purifying tower 2 enters the lower section of the drying tower of the first drying tower 4, the circulating dilute sulfuric acid (the concentration of the sulfuric acid is 75-80%) is sent out by a circulating pump 51 of the first drying tower, and is cooled to 12-15 ℃ by chilled water through a cooler 52 of the first drying tower, and then enters the upper section of the first drying tower 4 to be in countercurrent contact with the chlorine gas to remove the water in the chlorine. The concentration of the acid discharged from the tower bottom is controlled to be 75-80%. The water in the chlorine gas is absorbed by the sulfuric acid and gives up heat, which is largely removed by the first drying tower cooler 52. The second drying tower 6 is a bubble cap tower, the chlorine at the outlet of the first drying tower 4 enters the bottom of the second drying tower 6 and contacts with 98% concentrated sulfuric acid through a bubble cap, and after the concentrated sulfuric acid absorbs moisture in the chlorine, the concentration is reduced to 90% -95%, and then the chlorine automatically flows into the first drying tower 4. After absorbing water, the concentration of the sulfuric acid in the first drying tower 4 is reduced to 75-80%, and the dilute sulfuric acid is conveyed out of the battery compartment by a first tower circulating pump under the control of a liquid level adjusting system. The water content of the chlorine gas is reduced to be less than 100ppm after the drying of the secondary sulfuric acid, so that the quality of the purified and dried chlorine gas meets the requirement of the production of the bleaching powder, and the chlorine gas is compressed by a chlorine compressor 9 and then sent back to the chlorination process of the bleaching powder device.
The invention is not limited to the above alternative embodiments, and any other various forms of products can be obtained by anyone in the light of the present invention, but any changes in shape or structure thereof, which fall within the scope of the present invention as defined in the claims, fall within the scope of the present invention.
Claims (10)
1. The utility model provides a system for retrieve chlorine from useless mother liquor of high calcium hypochlorite essence, a serial communication port, including acidolysis cauldron (1), be connected with waste mother liquor pipe (12) that are used for adding hydrochloric acid pipe (11) in succession and add waste mother liquor in succession on acidolysis cauldron (1), there are purifying column (2) through the pipe connection in the gaseous phase export of acidolysis cauldron (1), be connected with circulation cold water pipe (3) that are used for the circulation to add the refrigerated water on purifying column (2), the gaseous phase export of purifying column (2) has first drying tower (4) through the pipe connection, be connected with circulation dilute sulfuric acid pipe (5) that are used for the circulation to add dilute sulfuric acid on first drying tower (4), the gaseous phase export of first drying tower (4) has second drying tower (6) through the pipe connection, be connected with concentrated sulfuric acid pipe (61) that are used for adding concentrated sulfuric acid on second drying tower (6).
2. The system for recovering chlorine from waste mother liquor of bleaching powder according to claim 1, wherein a liquid phase outlet of the acidolysis reactor (1) is connected with a liquid phase pipe (7), a pH monitor (71) is installed on the liquid phase pipe (7), a hydrochloric acid solenoid valve (111) is installed on the hydrochloric acid pipe (11), and the pH monitor (71) is electrically connected with the hydrochloric acid solenoid valve (111).
3. The system for recovering chlorine from the waste mother liquor of the bleaching powder as claimed in claim 1, wherein the gas phase outlet of the acidolysis kettle (1) is connected to the lower section of the purification tower (2) through a pipeline, and the outlet end of the circulating cold water pipe (3) is connected to the upper section of the purification tower (2).
4. The system for recovering chlorine from waste mother liquor of bleaching powder according to claim 3, characterized in that the inlet end of the circulating cold water pipe (3) is connected to the lower end of the purification tower (2), and the purification tower circulating pump (31) and the purification tower cooler (32) are installed on the circulating cold water pipe (3); still be connected with chlorine water pipe (8) that are used for discharging the chlorine water that contains chlorine dioxide on circulation cold water pipe (3), install chlorine water liquid level monitor (21) on purifying tower (2), install chlorine water solenoid valve (81) on chlorine water pipe (8), chlorine water liquid level monitor (21) is connected with chlorine water solenoid valve (81) electricity.
5. The system for recovering chlorine from the waste mother liquor of the bleaching powder according to claim 1, characterized in that the outlet end of the circulating dilute sulphuric acid pipe (5) is connected to the upper section of the first drying tower (4), and the gas phase outlet of the purifying tower (2) is connected to the lower section of the first drying tower (4) through a pipeline; the inlet end of the circulating dilute sulfuric acid pipe (5) is connected to the lower end of the first drying tower (4), and a first drying tower circulating pump (51) and a first drying tower cooler (52) are mounted on the circulating dilute sulfuric acid pipe (5); the circulating dilute sulfuric acid pipe (5) is connected with a dilute sulfuric acid discharge pipe (53), a dilute sulfuric acid electromagnetic valve (531) is installed on the dilute sulfuric acid discharge pipe (53), a dilute sulfuric acid liquid level monitor (62) is installed on the second drying tower (6), and the dilute sulfuric acid liquid level monitor (62) is electrically connected with the dilute sulfuric acid electromagnetic valve (531).
6. The system for recovering chlorine from the waste mother liquor of bleaching powder according to claim 5, characterized in that a sulfuric acid return pipe (63) is connected between the lower section of the second drying tower (6) and the lower section of the first drying tower (4).
7. The system for recovering chlorine from waste mother liquor of bleaching powder according to claim 1, characterized in that the gas phase outlet of the second drying tower (6) is connected with a chlorine press (9) through a pipeline, and the outlet of the chlorine press (9) is connected with a bleaching powder device through a pipeline.
8. A method for recovering chlorine from waste mother liquor of bleaching powder is characterized by comprising the following steps:
s1: continuously adding hydrochloric acid and waste mother liquor into an acidolysis kettle (1);
s2: sending acidolysis gas into a purification tower (2) to be fully contacted with circulating cold water;
s3: then the gas phase passes through a first drying tower (4) and a second drying tower (6) which are connected in series for drying.
9. The method for recovering chlorine from waste mother liquor of bleaching powder as claimed in claim 8, wherein in step S1, the addition rate of the waste mother liquor is constant, and the pH value of the liquid phase at the outlet of the acidolysis reactor (1) is set to 2-3 to adjust the addition rate of hydrochloric acid.
10. The method for recovering chlorine from waste mother liquor of bleaching powder according to claim 8, wherein in step S3, the first drying tower (4) is a bulk filler drying tower, the second drying tower (6) is a bubble cap tower, dilute sulfuric acid is added into the first drying tower (4), and concentrated sulfuric acid is added into the second drying tower (6).
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| CN115159462A (en) * | 2022-07-21 | 2022-10-11 | 宜宾海丰和锐有限公司 | Chlorine drying method for chlor-alkali production process |
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